The rubytail wasp (Chrysis ignita), is a species of the genus Chrysis, in the order Hymenoptera, the suborder Apocrita, the infraorder Aculeata, the superfamily Chrysidoidea, the family cuckoo wasps (Chrysididae), the subfamily Chrysidinae, and the tribe Chrysidini. Chrysis ignita are widespread in the Palaearctic ecozone of Europe and West Asia. In Central Europe, it is the most abundant species of cuckoo wasp.

Rubytail wasp - Side view

Adult rubytail wasps reach body lengths of 4 - 13 mm. Their size depends on the conditions of development? environmental conditions present during the larval stages. Their bodies are slim and vary in shape. The head and chest (thorax) are bright blue-green in colour. The upper surface has a metallic gold sheen. The upper surface of the abdomen shimmers red, copper red, purple or orange, while the underside is metallic blue or green. 4 teeth are visible at the rear edge of the back plates (tergite) of the last abdominal segment. The tergite has a finer punctation than those of the other segments.

Chrysis ignita in a spider web

Rubytail wasps prefer sunny, dry habitats up to high altitudes. They can be found from May to September on warm stone walls, wooden walls, telegraph poles and fences. The adults live off nectar from plants of the parsley family (Umbelliferae).

Rubytail wasp

After mating, the fertilized females lay their eggs separately in each brood cell in the nests of mason bees (Osmia), Anthophora, potter wasps (Eumenidae), pill wasps (Eumenes), Vespidae or sphecoid wasps (Spheciformes). The host insects try to prevent the rubytail wasps from entering their nests, however the latter are not only equipped with a strong chitin-armoured surface, but are also able to roll their bodies and thus significantly can reduce their body surface. This protects them against bites and helps them to penetrate the narrow passages of the host nests. Thus, the rubytail wasp remains largely intact, with the exception of the wings, which sometimes get damaged.

When the rubytail wasplarvae have hatched, they (after having scoured the aisles of the nest of food competitors) feed on the eggs or larvae of their hosts. Rubytail wasp larvae always hatch before their hostís larvae. Approximately 14 days after the rubytail wasp larvae hatch, even the food supplies of their hosts (only insects, no pollen) have been consumed, and they spin a cocoon for themselves in the hostís nest and pupate, either immediately, and then either to fly as another summer generation in the same year, or to overwinter inside of the cocoon. This assumes that the host larvae overwinter as well. The rubytail wasp is able to synchronize its development with the annual cycle of the various host larvae.